"Holmes said [the First Amendment] doesn't mean you can shout 'fire' in a crowded theater," Breyer told me. "Well, what is it? Why? Because people will be trampled to death. And what is the crowded theater today? What is the being trampled to death?"
Breyer is suggesting that any speech which could result in physical harm wouldn't be protected. This seems to be punishing Christians for mostly non-violent responses to what they consider offensive behavior while kowtowing to extremist Muslims on the grounds that they might hurt someone when they take offense at free speech.
via Jonathan Adler